Mechanical printer

ABSTRACT

A mechanical printer with a plurality of typing wheels which are pivotable separately from the carrier is provided in which an outer shaft which causes the typing wheels to revolve in unison around the axis thereof and an inner shaft which causes rotations of the typing wheels on their own axes are coupled to driving shafts through universal joints to permit the separate pivoting, and at least one driving shaft is provided with an Oldham&#39;&#39;s coupling obviating the need for strict alignment of the driving shafts.

United States Patent 191 Suzuki et al.

[5 1 MECHANICAL PRINTER [75] Inventors: Takaini Suzuki, Eujisawa; Koh

' Matsuhisa, Ninomiyamachi, both of Japan I [73] Assigne'e: Ricoh Co., Ltd.,'Tokyo, Japan 221 Filed: Apr. 27, 1972 [21] Appl. No.: 247,946

[30] Foreign Application Priority Data Apr. 30, 1971 Japan 46-28781 [52] US. Cl 197/18, 197/48, 197/55 [51] Int. Cl B4lj 23/04 [58] Field Of Search, 197/18, 48, 55

[56] v 5 References Cited UNITED STATES PATENTS 1,127,487 2/1915 Mohr 197/48 UX 3,272,302 9/1966 Segawa et al .1 197/50 [11]. 3,811,546 1451 May 21,1974

3,334,721 8/1967 Hickerson 197/50 3,356,198 12/1967 Michelotti 197/18 X 3,608,692 9/1971 Henry 197/55 Primary Examiner-Robert E. Pulfrey Assistant Examiner-Eugene H. Eickholt Attorney, Agent, or Firm-Cooper, Dunham, Clark, Griffin & Moran 7] ABSTRACT A mechanical printer witha plurality of typing wheels which are pivotable separately from the carrier is provided in which an outer shaft which causes the typing wheels to revolve in unison around the axis thereof and an inner shaft which causes rotations of the typing wheels on their own axes are coupled to driving shafts through universal joints to permit the separate pivoting, and at least one driving shaft is provided with an Oldhams coupling obviating the need for strict alignment of the driving shafts.

4 Claims, 4 Drawing Figures PATENTEDMYZI 1974 3'; 81 1 ,546

sum 1m 3 1 MECHANICAL PRINTER BACKGROUND OF THE INVENTION The present invention relates to a mechanical printer and more particularly a mechanical printer of the type in which a selected character on a cylindrical or ribbon-shaped typing head strikes through an inked ribbon a paper resting against a platen.

The mechanical printers of the type described above which are generally motor-driven are not only used in offices and the like but also used as output devices in electronic computers. In general, the mechanical printers of the type described use only one cylindrical or ribbon-shaped typing head around which are arranged inv rows various character types. However, when the number of characters used is increased, it becomes impossible to arrange them around only one typing head. To

overcome this problem, printers have been developed which have a typing head comprising a plurality of typing wheels, each having type characters arranged there around. Thesetyping wheels, for example four typing wheels are symmetrically arranged about the axis of an outer or hollow shaft which may not only rotate but also vertically move. An inner shaft is rotatably fitted into the outer shaft and is operatively coupled to the typing wheels through a gearing mechanism so that the rotation of the inner shaft may be transmitted simultaneously to the typing wheels independently of the rotation and translation of the outer shaftln order to select a desired character on the typing wheels, the typing wheel having this character is selected by rotating the outer shaft, then the row in which the desired character is positioned is selected by vertically moving the outer shaft, and the inner shaft rotates the selected typing wheel to bring the desired character in the selected row to a printing position.

In some of the mechanical printers of the type described, a rack and pinion are used to rotate the outer and inner shafts, and a desired row on the selected typing wheel is regulated by the vertical movement of the hammering frame or mechanism itself. Furthermore, an asynchronous system is employed in driving the outer and inner shafts and vertically moving the hammering frame or mechanism. In some types, the typing head is swiveled in unison with the carriage to deliver 'the stroke to the-paper resting against the platen;

Therefore, in the conventional mechanical printers of the type described, it has been impossible to select a desired character out of various characters arranged around the typing wheels with a high speed and to effect a rapid hammering action for printing.

One of the objects of the present invention is therefore to attain high-speed character selection and hammering action in mechanical printers of the type using a typing head comprising a plurality of typing wheels.

SUMMARY OF THE INVENTION whereas the rotation of the third driving shaft is converted into translational rotation through for example a rack and a pinion, wherein the translation of the rack is transmitted to the outer shaft for vertical motion thereof. Like the conventional mechanical printers-dc scribed, a desired typing wheel in the typing'head is selected by the rotation of the outer shaft; a desired row of the selected typing wheel is selected by the vertical movement of the outer shaft; and a desired character in the selected row on the selected typing wheel is selected by the rotation of the inner shaft.

According to the present invention, the driving shafts may rotate in either direction so that the angles of rotation of the driving shafts may be minimized in selecting a desired character, and it is not required to return the selected character to a reference position as in the conventional printers so that a desired character may be selected in a very short time. To deliver the stroke, only the typing head assembly is tilted or swiveled toward the platen about the axis of its pivots so that the high speed hammering action may be attained.

Furthermore, according to'the present invention, at least one of the three driving shafts'is used as a reference shaft for the movement of the carrier, and the remaining two driving shafts are providedwith Oldhams couplings through which the rotations of the driving shafts may be transmitted to the outer and inner shafts. Therefore the need for maintaining the correct parallelism among the driving shafts may be eliminated. Furthermore, no special consideration will be needed to be taken into account for overcoming the problems of parallelism and deflections of the driving shafts.

The above and other objects, features and advantages of the present invention will become more apparent from the following description of one preferred embodiment thereof taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING- FIG. 1 is a perspective view illustrating the major components of a mechanical printer in accordance with the present invention;

FIG. 2 is a sectional view taken along the line A-A of FIG. 1;

FIG. 3 is a fragmentary sectional view of a mechanism for controlling the drives of the typing wheels; and

FIG. 4 is a detailed view illustrating one of the driving shafts provided with an Oldhams coupling.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a platen or cylinder 1 is supported by stationary members (not shown) for rotation about the axis 2, and paper 3 rests against the platen 1. In parallel with the axis 2 are disposed three driving shafts, that'is an outershaft driving shaft 4, an inner shaft driving shaft 5, and a dri'ving'shaft for regulating the vertical movement of the outer shaft. These driving shafts 4, 5 and 6 are driven by for example pulse motors (not shown), and carry a carrier 7 which may be moved horizontally by appropriate means (not shown). A hammering frame 8 is mounted upon the carrier 7, and is adapted to tilt or swivel toward the platen 1 about the axis 9 when a selected character is printed. The hammering frame 8 carries four typing wheels 10,, 10 10 and 10 (the latter is not shown) insuch a manner that when the outer shaft 1 l rotates the typing wheels 10 revolve in unison around the axis of the outer shaft whereas when the inner shaft 12 fitted into the outer shaft 11 rotates, each of the typing wheels 10 are rotated on their own axes. Furthermore, the character rows of the typing wheels 10 are selected by the vertical movement of the outer shaft 11. Y

The rotation of the driving shaft 4 is transmitted to the outer shaft 11 through screw gears 25 and 24, gears 22 and 21, universal joints l9 and 18, and gears 17 and 16. Similarly the rotation of the driving shaft 5 is transmittedto the inner shaft 12 through a transmission comprising universal joints 26 and 27, gears 29, 30, and

screw gears 32 and 33. The rotation of the driving shaft.

6 is converted into the vertical translation through a rack 50 and a toothed segment 49. This vertical translation is transmitted through a suitable link mechanism (not shown) to an engaging member 51 of the outer shaft 11, thereby causing the vertical movement of the outer shaft 1 l in response to the rotation of the driving shaft 6. The mechanism for transmitting the motion of the rack 50 to the outer shaft 12 may be of any suitable type well known in the art.

Next referring to FIG. 2 where the parts illustrated in FIG. 1 are designated by the same reference numerals, the construction and mode of operation of the hammering mechanism will be described in detail. Along the vertical axis of the hammering frame 8 is fitted the outer shaft 11 into which is fitted the inner shaft 12. Lower and upper stems l3 and 13 are fitted over the outer shaft 11 in vertically spaced apart relation, and the four typing wheels are pivoted for rotation between the lower and upper stems l3 and 13. (In FIG. 2, of the four typing wheels 10, only two typing wheels 10 and 10 are shown.) Gears 14 and 14 fixed to the lower ends of the typing wheels 10 and 10 are in mesh with a gear 15 carried by the inner'shaft 12 forming a planetary gear mechanism through which the rotation of the inner shaft 12 may be transmitted to the typing wheels 10 and 10 for rotation about their own axes. The gear 16 carried by'the lower end of the outer shaft 11 is in mesh with a gear 17 which is drivingly coupled to a shaft through the universal joints 18 and 19. Keys (not shown) fixed to the gears 15 and 16 are fitted into keyways (not shown) on the inner and outer shafts l2 and 11 sojthat the gears 15 and 16 may not only rotate in unison with the inner shaft 12 and outer shaft 11 respectively but the respective parts also may move vertically relative to each other. The shaft 20 which is carried by the carrier 7 has the gear 21 in mesh with the I gear 22 carried by a shaft 23 which also carries the screw gear 24 below the gear 22.

Referring back to FIG. 1, the gear 24 is in mesh with the screw gear 25 carried by the driving shaft 4. Thus, the rotation of the driving shaft 4 is transmitted to the outer shaft 11 so that the typing wheels 10 may be ro-.

tated about the axis of the outer shaft 11.

Referring back to FIG. 2 again, the inner shaft 12 fitted into the outer shaft 11 is coupled to a shaft 28 through the pair of universal joints 26 and 27, and the shaft 28 is supported in the carrier 7. The gear 29 carried by the shaft 28 is in mesh with the gear 30 carried by a shaft '31, and the screw gear 32 carried by the shaft 31 is in mesh with the screw gear 33 carried by the driving shaft 5 (See FIG. 1). Thus, the rotation of the driving shaft 5 is transmitted to the inner shaft 12 and then to the typing wheels 10 through the gear 15 whereby each of them is rotated about its own axis.

As described above, the engaging member 51 is fixed to the outer shaft 11 so that the rotation of the driving shaft 6 which has been converted into vertical translational motion is transmitted to the engaging member 51 which in turn causes the vertical movement of the outer shaft 11. The hammering frame 8 which is supported by a pair of pivot bearings 52 and 52 is caused to tilt or swivel toward the platen 1 about the axis of the pivot bearings when the stroke is delivered.

Next-referring to FIG. 3, the keyways 4, 5, and 6 are machined in the driving shafts 4, 5, and 6 respectively. The screw wheel 25 is keyed to the driving shaft 4 with a key 25' fitted into the keyway 4'. Therefore, the screw wheel 25 may not only rotate in unison with the driving shaft 4 but also move lengthwise thereof. The hub of the screw wheel 25 is supported by roller bearings 34 and 35 which in turn are securely fixed to the carrier 7. The rotation of the driving shaft 4 is transmitted to the outer shaft 11 through the worm wheel 25, the worm 24, the gears 22 and 21 and the universal joints 18 and 19 (See FIG. 2).

The rotations of the driving shafts 5 and 6 are transmitted to the hammering frame mechanism through an Oldhams coupling so that the problems of parallelism and deflections of the driving shafts 5, 6 and 7 may be overcome. v

A slotted disk 36 is keyed to the driving shaft 5 with a key 36' fitted into the keyway 5', and engages with an intermediate disk 37 'with two projections which in turn engages with a slotted disk 38. The disks 36, 37, and 38 constitute an Oldhams coupling. The screw wheel 33 is carried by the slotted disk 38, and is also supported by a roller bearing 39 and thrust bearings 40 and 41 which in turn are fixed to the carrier 7. The right ball bearing 41 is securely held in position with nuts 42. Short spacings are provided between the disks 37, 38 and the gear 33 and the driving shaft 5. The details of the Oldhams coupling 36, 37 and 38 of the driving shaft 5 and its associated components are illustrated in exploded view in FIG. 4 for facilitating the understanding of the arrangement of the disks of the Oldhams coupling 36, 37 and 38. The rotation of the driving shaft 5 is transmitted through the Oldhams coupling 36, 37, and 38 to the gear 33 and then to the inner shaft 12 through the gears 32, 30, and 29. Similarly the driving shaft 6 has an Oldhams coupling comprising a disk 43 keyed to the shaft 6 with a key 43 fitted into the keyway 6' and a disk 44 in engagement with the disk 43. The disk 44 carries the toothed segment 49 which is supported by the bearings, 45, 46, and 47 whicn in turn are fixed to the carrier 7. The bearing 47 is securely held in position by nuts 48. Plays are provided between the driving-shaft 6 and. the disk 44 and the toothed segment 49. The rotation of the driving shaft 6 is transmitted through the Oldhams coupling 43 and 44 to the toothed segment 49 which is in mesh with the rack 50 so that the rotation of thedriving shaft 6 is converted into the translation. The translation of the rack 50 is transmitted to the outer shaft 11.

Referring back to FIG. 3, the driving shaft 4 is the reference shaft for the movement of the carrier 7, and

' even though the driving shafts 5 and 6 are not correctly in parallel with the reference shaft 4 or deflected, the carrier 7 may be moved over the driving shafts 4, Sand 6 while the rotations thereof are positively transmitted to the outer and inner shafts 11 and 12. Instead of the driving shaft 4, the driving shaft 5 or 6 may be selected as a reference shaft or two driving shafts may be selected as reference shafts whereas only the remaining shaft is provided with an Oldhams coupling.

What is claimed is:-

l. A mechanical printer comprising:

first, second and third rotary driving shafts disposed in parallel relative to each other and to a platen;

a carrier mounted for movement along said driving shafts adjacent said platen;

a printing mechanism mounted upon said carrier and pivotable thereon toward said platen for printing a selected character, said printing mechanism in cluding:

a supporting frame;

a pivot means for directly mounting said supporting frame on said carrier;

a hollow outer shaft vertically and rotatably mounted on said supporting frame;

a plurality of typing wheels mounted for rotation on said outer shaft and symetrically disposed about the axis of said outer shaft with respect to each other; and

a planetary gear mechanism rotatablymounted on said supporting frame and connected to said typ- 4 ing wheels;

an inner shaft fitted into and extending through said outer shaft and rotatably coupled to said typing wheels through said planetary gear mechanism;

a first transmission mechanism connected between said first driving shaft and said outer shaft for transmitting the rotation of said first driving shaft to said outer shaft;

a second transmission mechanism connected be-' tween said second driving shaft and said inner shaft for transmitting the rotation of said second driving shaft to said inner shaft; and first and second universal joints respectively coupling said first and second transmission mechanisms to said outer shaft and said inner shaft such that said driving shafts are coupled to said outer and inner shafts through universal joints, permitting the pivoting of said printing mechanism with respect to said carrier when printing. 2. A mechanical printer as in claim 1 further comprising a third transmission mechanism connected between said third driving shaft and said outer shaft for converting the rotation of said third driving shaft into I the vertical translation of said outer shaft.

3. A mechanical printer as in claim 2 wherein at least one of said first, second, and third rotary driving shafts is provided with an Oldhams coupling for transmitting the rotation thereof to its associated transmission mechanism.

4. A mechanical printer as in claim 3, wherein at least one of the other of said first, second and third rotary driving shafts which is not provided with an Oldhams coupling is coupled to said carrier for guiding the movement thereof. 

1. A mechanical printer comprising: first, second and third rotary driving shafts disposed in parallel relative to each other and to a platen; a carrier mounted for movement along said driving shafts adjacent said platen; a printing mechanism mounted upon said carrier and pivotable thereon toward said platen for printing a selected character, said printing mechanism including: a supporting frame; a pivot means for directly mounting said supporting frame on said carrier; a hollow outer shaft vertically and rotatably mounted on said supporting frame; a plurality of typing wheels mounted for rotation on said outer shaft and symetrically disposed about the axis of said outer shaft with respect to each other; and a planetary gear mechanism rotatably mounted on said supporting frame and connected to said typing wheels; an inner shaft fitted into and extending through said outer shaft and rotatably coupled to said typing wheels through said planetary gear mechanism; a first transmission mechanism connected between said first driving shaft and said outer shaft for transmitting the rotation of said first driving shaft to said outer shaft; a second transmission mechanism connected between said second driving shaft and said inner shaft for transmitting the rotation of said second driving shaft to said inner shaft; and first and second universal joints respectively coupling said first and second transmission mechanisms to said outer shaft and said inner shaft such that said driving shafts are coupled to said outer and inner shafts through universal joints, permitting the pivoting of said printing mechanism with respect to said carrier when printing.
 2. A mechanical printer as in claim 1 further comprising a third transmission mechanism connected between said third driving shaft and said outer shaft for converting the rotation of said third driving shaft into the vertical translation of said outer shaft.
 3. A mechanical printer as in claim 2 wherein at least one of said first, second, and third rotary driving shafts is provided with an Oldham''s coupling for transmitting the rotation thereof to its associated transmission mechanism.
 4. A mechanical printer as in claim 3, wherein at least one of the other of said first, second and third rotary driving shafts which is not provided with an Oldham''s coupling is coupled to said carrier for guiding the movement thereof. 